Chemistry Year 11 - Module 4 - Lesson 12
📊 Calculating ΔS° & Standard Entropy
1. Key Ideas
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- Key facts and terms for 📊 Calculating ΔS° & Standard Entropy
- How the main ideas in 📊 Calculating ΔS° & Standard Entropy connect
2. Success Criteria
By the end, you should be able to:
- Key facts and terms for 📊 Calculating ΔS° & Standard Entropy
- Where this lesson fits in Module 4
- How the main ideas in 📊 Calculating ΔS° & Standard Entropy connect
3. Key Terms
4. Activity: Build the Lesson Map
Use the lesson to complete the table. Keep answers brief but specific.
| Prompt | Your answer |
|---|---|
| Main concept | |
| Important example | |
| Common mistake to avoid | |
| How this links to the next lesson |
5. Short Answer Questions
1. Q6 (4 marks) Explain the Third Law of Thermodynamics and why it allows us to tabulate absolute entropy values (S°) for all substances. In your answer, explain why S°(elements) ≠ 0, unlike ΔHf°(elements) = 0.
2. Q7 (5 marks) Calculate ΔS° for the formation of ammonia: $\text{N}_2\text{(g)} + 3\text{H}_2\text{(g)} \to 2\text{NH}_3\text{(g)}$. Then convert ΔS° to kJ K⁻¹ mol⁻¹ and explain when this conversion is necessary. Use: S°[N₂(g)] = 191.6, S°[H₂(g)] = 130.7, S°[NH₃(g)] = 192.4 J K⁻¹ mol⁻¹.
3. Q8 (6 marks) The combustion of methane is: $\text{CH}_4\text{(g)} + 2\text{O}_2\text{(g)} \to \text{CO}_2\text{(g)} + 2\text{H}_2\text{O(l)}$. ΔH° = −890 kJ mol⁻¹. Using the data table from Activity 1, calculate ΔS° for this reaction. Then determine ΔG° at 25°C (298 K) and comment on whether the reaction is spontaneous at this temperature. Show all working and unit conversions.
6. Extend: Apply the Idea
A student gives a memorised answer about 📊 Calculating ΔS° & Standard Entropy but does not use evidence or reasoning.
Improve the answer by writing a stronger response that uses accurate terminology, a relevant example and a clear explanation.
7. Multiple Choice
1. What is the best first step when answering a question about 📊 Calculating ΔS° & Standard Entropy?
A. Identify the key concept being tested
B. Write every fact from memory
C. Ignore the command word
D. Skip examples and evidence
2. Which answer would show stronger understanding of 📊 Calculating ΔS° & Standard Entropy?
A. An answer with accurate terms and reasoning
B. A copied definition only
C. A single-word response
D. An answer with no example
3. What should you do if a question asks you to explain?
A. Link the idea to a reason or cause
B. List unrelated facts
C. Only draw a diagram
D. Write the shortest possible answer
8. Success Criteria Proof
Finish with evidence that you can do each success criterion.